amorphous, black, pitchy form of the crystalline uranium oxide (uranium processing) mineral uraninite (q.v.); it is one of the primary mineral ores of uranium, containing 50–80 percent of that element. Three chemical elements were first discovered in pitchblende: uranium by the German chemist Martin Klaproth in 1789, and polonium and radium by the French scientists Pierre and Marie Curie in 1898. Deposits, frequently in association with uraninite or with secondary uranium minerals, are known in Congo (Kinshasa); the Czech Republic; England; the Northwest Territories and Saskatchewan in Canada; and Arizona, Colorado, Montana, New Mexico, and Utah in the United States.